Measurement of the top quark mass at D0

The most recent measurements of the mass of the quark top at D0 are reviewed. The analysis methods include the direct measurement by Matrix Element and Weighting method and the indirect measurement from t{bar t} production cross section. They have been applied on different experimental signatures, all including at least one electron or muon. Measurements include from 1 to 3.6 fb{sup -1} of D0 data. The most recent combination of mass measurements from D0 and from CDF are also quoted

W Asymmetry and Z Rapidity Measurements

The measurements of W charge asymmetry and Z rapidity distributions are inputs to constrain the parton distribution functions at high Q{sup 2}. The CDF and D0 experiments at the Tevatron have analyzed up to 340 pb{sup -1} of Run 2 data to measure the W charge asymmetry and Z rapidity. The measurements are in generally good agreement with predictions

QCD Radiation in the Production of High s-hat Final States

In the production of very heavy final states - high Mandelstam s-hat - extra QCD radiation can play a significant role. By comparing several different parton shower approximations to results obtained with fixed-order perturbation theory, we quantify the degree to which these approaches agree (or disagree), focussing on initial state radiation above pT = 50 GeV, for top pair production at the Tevatron and at the LHC, and for SUSY pair production at the LHC. Special attention is paid to ambiguities associated with the choice of the maximum value of the ordering variable in parton shower models.Comment: Invited talk at 2005 International Linear Collider Physics and Detector Workshop and Second ILC Accelerator Workshop, Snowmass, CO (Snowmass05), 5 pages, LaTeX, 3 eps figure

Electron beam size measurements in the Fermilab Electron Cooling System

The Fermilab Electron Cooling Project requires a straight trajectory and constant beam size to provide maximum cooling of the antiprotons in the Recycler. A measurement system was developed using movable apertures and steering bumps to measure the beam size in a 20m long, nearly continuous, solenoid. This paper will focus on results of these measurements of the beam size and the difficulties in making those measurements

Tevatron-for-LHC Report of the QCD Working Group

The experiments at Run 2 of the Tevatron have each accumulated over 1 fb{sup -1} of high-transverse momentum data. Such a dataset allows for the first precision (i.e. comparisons between theory and experiment at the few percent level) tests of QCD at a hadron collider. While the Large Hadron Collider has been designed as a discovery machine, basic QCD analyses will still need to be performed to understand the working environment. The Tevatron-for-LHC workshop was conceived as a communication link to pass on the expertise of the Tevatron and to test new analysis ideas coming from the LHC community. The TeV4LHC QCD Working Group focused on important aspects of QCD at hadron colliders: jet definitions, extraction and use of Parton Distribution Functions, the underlying event, Monte Carlo tunes, and diffractive physics. This report summarizes some of the results achieved during this workshop

A Proposal to Search for Charmed Particle Production Near Threshold

We propose to search for charmed particle production thresholds by looking for anomalies in the ratio of K{sup -}/{pi}{sup -} production at P{sub T} {approx} 1 GeV/c as the incident energy is varied. Any anomalous behavior will be further investigated using a two arm effective mass spectrometer

Decay Properties of p pi- Systems Produced in Neutron Dissociation at Fermilab Energies

The authors have examined the decay distributions of (p{pi}{sup -}) systems produced in the reaction n + p {yields} (p{pi}{sup -}) + p for neutron momenta between 120 GeV/c and 300 GeV/c. Preliminary analysis of decay moments indicates the presence of large helicity-flip amplitudes even for small (p{pi}{sup -}) mass values, and does not support the hypothesis that the helicity non-flip (p{pi}{sup -}) states are produced peripherally in impact parameter. These results are in approximate agreement with predictions of the Deck mechanism. The experiment was performed at the M-3 neutral beam of Fermilab

Impact of astrophysical processes on the gamma-ray background from dark matter annihilations

We study the impact of astrophysical processes on the gamma-ray background produced by the annihilation of dark matter particles in cosmological halos, with particular attention to the consequences of the formation of supermassive black holes. In scenarios where these objects form adiabatically from the accretion of matter on small seeds, dark matter is first compressed into very dense 'spikes', then its density progressively decreases due to annihilations and scattering of stellar cusps. With respect to previous analyses, based on non-evolving halos, the predicted annihilation signal is higher and significantly distorted at low energies, reflecting the large contribution to the total flux from unevolved spikes at high redshifts. The peculiar spectral feature arising from the specific redshift distribution of the signal, would discriminate the proposed scenario from more conventional astrophysical explanations. We discuss how this affects the prospects for detection and demonstrate that the gamma-ray background from DM annihilations might be detectable even in absence of a signal from the Galactic center

Search for time-dependent B0s - B0s-bar oscillations using a vertex charge dipole technique

We report a search for B0s - B0s-bar oscillations using a sample of 400,000 hadronic Z0 decays collected by the SLD experiment. The analysis takes advantage of the electron beam polarization as well as information from the hemisphere opposite that of the reconstructed B decay to tag the B production flavor. The excellent resolution provided by the pixel CCD vertex detector is exploited to cleanly reconstruct both B and cascade D decay vertices, and tag the B decay flavor from the charge difference between them. We exclude the following values of the B0s - B0s-bar oscillation frequency: Delta m_s < 4.9 ps-1 and 7.9 < Delta m_s < 10.3 ps-1 at the 95% confidence level.Comment: 18 pages, 3 figures, replaced by version accepted for publication in Phys.Rev.D; results differ slightly from first versio